Detection rules › Sublime MQL

Service abuse: Google application integration redirecting to suspicious hosts

Severity
medium
Type
rule
Source
github.com/sublime-security/sublime-rules

Detects legitimate Google application integration emails that contain links redirecting to free file hosting services or free subdomain hosts, including Microsoft OAuth redirects to suspicious domains. These could indicate abuse of Google's legitimate service for malicious redirects.

Threat classification

Sublime's own taxonomy (not MITRE ATT&CK).

CategoryValues
Attack typesCredential Phishing, Malware/Ransomware
Tactics and techniquesEvasion, Free file host, Free subdomain host, Open redirect

Event coverage

Rule body MQL

type.inbound
and sender.email.email == "noreply-application-integration@google.com"
and headers.auth_summary.dmarc.pass
and length(body.links) < 10
and any(body.links,
        .href_url.domain.domain in $free_file_hosts
        or .href_url.domain.root_domain in $free_file_hosts
        or .href_url.domain.domain in $free_subdomain_hosts
        // Mimecast link logic
        or (
          .href_url.domain.root_domain in (
            "mimecastprotect.com",
            "mimecast.com"
          )
          and any(.href_url.query_params_decoded['domain'],
                  strings.parse_domain(.).domain in $free_file_hosts
                  or strings.parse_domain(.).root_domain in $free_file_hosts
                  or strings.parse_domain(.).root_domain in $free_subdomain_hosts
                  or . in (
                    "storage.cloud.google.com",
                    "login.microsoftonline.com"
                  )
          )
        )
        or network.whois(.href_url.domain).days_old < 30
        // abuse observed
        or .href_url.domain.root_domain == "share.google"
)

Detection logic

Scope: inbound message.

Detects legitimate Google application integration emails that contain links redirecting to free file hosting services or free subdomain hosts, including Microsoft OAuth redirects to suspicious domains. These could indicate abuse of Google's legitimate service for malicious redirects.

  1. inbound message
  2. sender.email.email is 'noreply-application-integration@google.com'
  3. headers.auth_summary.dmarc.pass
  4. length(body.links) < 10
  5. any of body.links where any holds:
    • .href_url.domain.domain in $free_file_hosts
    • .href_url.domain.root_domain in $free_file_hosts
    • .href_url.domain.domain in $free_subdomain_hosts
    • all of:
      • .href_url.domain.root_domain in ('mimecastprotect.com', 'mimecast.com')
      • any of .href_url.query_params_decoded['domain'] where any holds:
        • strings.parse_domain(.).domain in $free_file_hosts
        • strings.parse_domain(.).root_domain in $free_file_hosts
        • strings.parse_domain(.).root_domain in $free_subdomain_hosts
        • . in ('storage.cloud.google.com', 'login.microsoftonline.com')
    • network.whois(.href_url.domain).days_old < 30
    • .href_url.domain.root_domain is 'share.google'

Inspects: body.links, body.links[].href_url.domain, body.links[].href_url.domain.domain, body.links[].href_url.domain.root_domain, body.links[].href_url.query_params_decoded['domain'], headers.auth_summary.dmarc.pass, sender.email.email, type.inbound. Sensors: network.whois, strings.parse_domain. Reference lists: $free_file_hosts, $free_subdomain_hosts.

Indicators matched (6)

FieldMatchValue
sender.email.emailequalsnoreply-application-integration@google.com
body.links[].href_url.domain.root_domainmembermimecastprotect.com
body.links[].href_url.domain.root_domainmembermimecast.com
body.links[].href_url.query_params_decoded['domain'][]memberstorage.cloud.google.com
body.links[].href_url.query_params_decoded['domain'][]memberlogin.microsoftonline.com
body.links[].href_url.domain.root_domainequalsshare.google